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1.5" C:B ratio - test data
This C:B test using two different ammunition was the most intensive test to date conducted at Burnt Latke. Every measure was taken to maintain consistency and approximate real world shooting conditions. Despite the care taken with this test, the results are inconclusive.
It does appear that each ammo attained the highest velocity at one specific ratio although the neighboring ratios provide nearly the same speeds. The low friction gasket slug maxed out at .8:1 as expected but surprisingly, the higher friction spuds required an even longer barrel to attain their fastest velocity. This seems contradictory as a higher friction ammo would appear to require a shorter barrel for maximum efficiency.
Also of concern is the fact that gasket slugs were shooting faster at the shorter 1.4 ratio than 1.3. The data for these ratios is not complete as only 4 shots were done at the shorter lengths. This is due to the fact that this test extended into the evening and the L1 was becoming increasingly louder as the barrel became shorter. Also there may have been buildup of rubber or starch inside the barrel that affected the results of the later ratios, despite the firing of paper towels through the barrel at each ammo change. This was evidenced the next day when we tried to pick up the 1.5:1 and 1.6:1 ratios neglected the first day of testing. Before the reshoot, the remaining barrel was cleaned which was when a flaky, char-broiled buildup was detected and removed. After this cleaning, the 1.5 barrel was shooting slugs at 395 and spuds at 340 MPH while the 1.6 barrel recorded 389 and 334 MPH respectively. These high speeds at the shorter lengths did not mesh with the first days results pointing to some kind of buildup affecting the measurements.
Another test similar to this will be conducted in the future using only potatos as ammunition and the new 3 litre, L3 launcher. Higher standards of consistency will be utilized and the barrel will be cleaned with water and dried routinely during the test. The new test, along with the data here, should help paint a clear picture of chamber to barrel ratio performance on full sized combustion launchers.
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